This invention relates to the diffusing of one fluid within another, and particularly to a diffuser apparatus that repeatedly forms and reforms globules or bubbles of the one fluid for dispersal in a pool of the other fluid.
Fluid diffusers are commonly employed to aerate wastewater as part of the biological treatment of the wastewater. The diffusers are submerged in the wastewater and discharge bubbles of air that ascend through the wastewater. This results in a transfer of oxygen between the bubbles of air and the wastewater. The oxygen is used for respiration by organisms that feed on the impurities in the wastewater and thereby remove the impurities.
One common form of fluid diffuser discharges the air through one or more outlets in a circular array to more widely disperse the bubbles of air. Examples of this form of diffuser are found in the following U.S. Pat. Nos.: 3,334,819 issued Aug. 8, 1967 to Olavson; 3,525,436 issued Aug. 25, 1970 to Reckers; 3,997,634 issued Dec. 14, 1976 to Downs; 4,597,530 issued Jul. 1, 1986 to Goudy, Jr. et al.; and 4,629,126 issued Dec. 16, 1986 to Goudy, Jr. et al..
Other forms of fluid diffusers use porous stones, either natural or man-made, slit tubes, porous fabric socks, and perforated plates, all for the purpose of changing the entering stream of air into bubbles.
The oxygen transfer between the bubbles and the surrounding wastewater takes place at the surface of the bubbles. Therefore, it is important to maximize the surface areas of the bubbles to the greatest extent possible to thereby maximize the oxygen transfer. Generally, the surface area of the bubbles is maximized by forming many fine bubbles. However, as the bubbles rise within the pool of wastewater, they tend to combine or agglomerate into larger bubbles with the result that the total surface area is reduced. This negatively impacts on the rate of oxygen transfer.
The present invention provides apparatus and method for maximizing the surface area of the air bubbles as they pass through the wastewater. The surface area is maximized by collecting the bubbles after they agglomerate and then reforming them as smaller discrete bubbles. This is accomplished as the air moves from the depths of the pool of wastewater to the surface thereof.
Although the invention has particular application to fluid diffusers for aerating wastewater, it is applicable to the dispersal of any one fluid, either gas or liquid, into a pool of a second fluid.